Influence of moderate altitude on blood lactate and heart rate in a standardized exercise test in healthy volunteers

Abstract

Nineteen healthy volunteers were exposed to a standardized exercise test at sea level (SLa), at an altitude of 1700 m before (1700a) and after a moderate 10-day mountain training (1700b), with a final control four weeks later at sea level (SLb). Vital signs, blood lactate and arterial oxygen saturation were determined prior, during or after the exercise test. Whereas systolic blood pressure and heart rate at rest did not change substantially, diastolic blood pressure decreased at the final control (SLb, p<0.05) and oxygen saturation was significantly lower at 1700 m (1700a, 1700b, p<0.01). Lactate at rest increased from 1.16 (SLa) to 1.97 (1700a) mmol/l after acute exposure followed by a slight reduction after adaptation (p<0.05). The mean maximum lactate levels were as follows: 6.03, 10.56, 6.22 and 8.75 (p<0.01). The mean maximum performance increased during the study (225.6, 223.3, 231.6, 248.1 Watt, p<0.01). Lactate versus workload curves did not show a marked shift to the right. No significant changes of maximum heart rates during the exercise test were found. In conclusion, a sojourn at 1700 m provokes an increase of lactate levels with subsequent reduction after acclimatization and has a significant positive impact on the mean maximum performance after moderate mountain training.